<!DOCTYPE HTML>
<html>
<head>
    <meta charset="utf-8">
    <title>菜鸟教程(runoob.com)</title>
    <style>
        .error {color: #FF0000;}
    </style>
</head>
<body>

<?php
/**
 * 正则表达式匹配，preg_match（）
 * preg_match()
 */
// 定义变量并默认设置为空值
$nameErr = $emailErr = $genderErr = $websiteErr = "";
$name = $email = $gender = $comment = $website = "";

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    if (empty($_POST["name"])) {
        $nameErr = "Name is required";
    } else {
        $name = test_input($_POST["name"]);
        // 检测名字是否只包含字母跟空格
        if (!preg_match("/^[a-zA-Z ]*$/",$name)) {
            $nameErr = "只允许字母和空格";
        }
    }

    if (empty($_POST["email"])) {
        $emailErr = "Email is required";
    } else {
        $email = test_input($_POST["email"]);
        // 检测邮箱是否合法
        if (!preg_match("/([\w\-]+\@[\w\-]+\.[\w\-]+)/",$email)) {
            $emailErr = "非法邮箱格式";
        }
    }

    if (empty($_POST["website"])) {
        $website = "";
    } else {
        $website = test_input($_POST["website"]);
        // 检测 URL 地址是否合法
        if (!preg_match("/\b(?:(?:https?|ftp):\/\/|www\.)[-a-z0-9+&@#\/%?=~_|!:,.;]*[-a-z0-9+&@#\/%=~_|]/i",$website)) {
            $websiteErr = "非法的 URL 的地址";
        }
    }

    if (empty($_POST["comment"])) {
        $comment = "";
    } else {
        $comment = test_input($_POST["comment"]);
    }

    if (empty($_POST["gender"])) {
        $genderErr = "性别是必需的";
    } else {
        $gender = test_input($_POST["gender"]);
    }
}

function test_input($data) {
    $data = trim($data);
    $data = stripslashes($data);
    $data = htmlspecialchars($data);
    return $data;
}
?>

<h2>PHP 表单验证实例</h2>
<p><span class="error">* 必需字段。</span></p>
<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">
    名字: <input type="text" name="name">
    <span class="error">* <?php echo $nameErr;?></span>
    <br><br>
    E-mail: <input type="text" name="email">
    <span class="error">* <?php echo $emailErr;?></span>
    <br><br>
    网址: <input type="text" name="website">
    <span class="error"><?php echo $websiteErr;?></span>
    <br><br>
    备注: <textarea name="comment" rows="5" cols="40"></textarea>
    <br><br>
    性别:
    <input type="radio" name="gender" value="female">女
    <input type="radio" name="gender" value="male">男
    <span class="error">* <?php echo $genderErr;?></span>
    <br><br>
    <input type="submit" name="submit" value="Submit">
</form>

<?php
echo "<h2>您输入的内容是:</h2>";
echo $name;
echo "<br>";
echo $email;
echo "<br>";
echo $website;
echo "<br>";
echo $comment;
echo "<br>";
echo $gender;
?>

</body>
</html>
